How does javascript determine whether the data entered in the control is a numeric type?

Judgment method: 1. Use the "input control object.value" statement to obtain the data entered by the user; 2. Use "var re = /^[0-9] .?[0-9]*/; " statement defines a regular expression object; 3. Use the "re.test (input data)" statement to determine whether the input data is a numeric type through a regular expression.

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

javascript determines that the data entered in the control is of numerical type

• First you need to use the value attribute to get the value of the input control ;

• Then use regular expressions and the test() function to determine whether the data entered in the control is of numerical type.

Implementation code:

<input id="num" placeholder="请输入数值" /><br><br>
<button id="btn">判断类型</button>
<script>
	function my(id) {
		return document.getElementById(id);
	}
	my("btn").onclick = function() {
		var val = my("num").value;
		var re = /^[0-9]+.?[0-9]*/;//判断字符串是否为数字//判断正整数/[1−9]+[0−9]∗]∗/
		if (re.test(val)) {
			console.log("输入的是数值类型");
		} else {
			console.log("输入的不是数值类型，请重新输入");
		}
	}
</script>

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